Directive radio repeating system



May s, 1928. 1,668,674

' L. ESPENSCHIED ET AL DIRECTIVE RADIO REPEATING SYSTEM Filed Dec. 28. '1921 3 Sheets-Sheet 1 J WW;

ATTORNEY Patented May 8 1928.

UNITED STATES PATENT OFFICE.

LLOYD ESPENSCHIED, 0F QUEENS, NEW YORK. AND DE LOSS K. MARTIN, OI ORANGE, NEW JERSEY, ASSIGINORS TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY,

A CORPORATION OF NEW YORK.

DIRECTIVE RADioRErEATiNG SYSTEM.

Application filed December 28, 1921. Serial No. 525,441.

'lhisinveiution relates to directive radio repeating systems and particularly to that type of system in which transmission and reception are effected at the same frequency. In our copending application, Serial No. 525,440 filed December 28, 1.921, various forms of circuits are shown for relaying radio signals in which transmission and re ception are effected at the same frequency. In. the forms shown in the said copcnding application, the direction characteristic of the antenna arrays is of the bilateral type in which both reception and transmission of energy is effected in two diametrically opposite directions from the array.

It is one of the objects of the present in vention to provide a radio relay adjusted to have a direction characteristic which is either unilateral or duolateral. Unilateral means that theantenna array capable of receiving efliciently from only one direction, and, likewise of transmitting efficiently in only one directionj and duolateral means reception from two directions less than 180 degrees apart, and, likewise, transmission from two directions less than 180 degrees apart. i i Another object of this invention is to provide a long distance signaling system in which the effects of. static are minimized by the use of short waves, which, as is well known, are less affected by static than are long waves. Furthermore, the effect of static may be minimized by sustaining throughout the course of transmission the ratio of the signaling energy to static, which result may be attained by spacing the directive repeat-- ing stations at certain predetermined points. depending upon the drop in the energy level between the successive repeating stations.

By the use of repeating stationsembodv ing directive antenna arrays and their as sociated amplifying circuits, the course of transmission of signals between widely scparated terminals may be controlled, since it is practicable, by properly locating'the repeat ing stations, to direct the transmission either along astraight line between the two terminals, or along a more devious course. This feature of our invention becomes important when it is desired to avoid objects lying between the two terminals which would tendto interfere with the propagation of electromagnetic waves, or when, for traflic or other reasons, it would be desirable to transmit the signals over the more indirect route.

This invention will he better-understood from the following description when read in connection with the attached drawing, of which Figure 1 shows an arrangement in which. reception and transmission are effected callythe frequency distribution throughout the system; Fig. shows a unit circuit of an array using balancedvertical and ground antennae for duplex operation, and Fig.4 s a characteristic of the array; Fig. his a duolateral characteristic'of a system such as Fig; under proper adjustment; Fig. 5' shows optional arrangements of the array, and Fig. 5 shows graphically the frequency distribution: and Fig. 6 shows a method for separating the repeating stations, which is rendered possible by directive control of radiation and reception, whereby singing between channels is prevented.

In Fig. 1. X X,, X, and X represent four vertical antennae which are spaced apart a definite fraction of a wave length, as shown in the drawing. Connected with the antenna X, by means of a triple-wind ing transformer or hybrid coil T,, is a local. circuit comprising a phase shifting device PS a band filter F,, a low power amplifier A a power amplifier A another band filter F,, and another phase shifting device PS ..This local circuit is connected with the windings of the transformer T in a manner well known to those familiar with the art, and the said transformerhas also connected thereto a network N,, which is designed to balancethe antenna X Each antenna of the array has connected thereto a circuitsimilar to and embodying the same apparatus as that described in connection with the antenna X In the operation of the system shown in this figure, when oscillations of the frequency of i 18 are setup in each of the antennae of the array, asfor example X,,

the current at this frequency will pass into the input branch 1 of the repeater circuit and will be impressed upon the phase shiftin device PS,, which is designed to contI'Ol the phase of the current applied to the subsequent amplifying devices in this local circuit. Current of the frcipieuey of f,::s will pass through the band filter F, and be amplified by the low power amplifier A,. This amplifier may be a single stage type,

although it is customary and undoubtedly desirable to use a plurality of stages in order to build up the potential applied to the power amplifier A The output current of the latter amplifier is transn'iitted through a band filter F having preferably the same frequency transmission range as F,, and is then passed through the phase shifting device PS which controls the phase at which the current is applied to the antennaX, for radiation therefrom. It is tov be understood that similar action is going on simultaneously in the other antennae, constituting the array, and in the local circuits individual to the said antcnnze. By controlling the phase of the current by means of the phase shifting devices PS and PS associated with the local circuits of each antenna in a manner fully described in the copending application of George A. Campbell, Serial No. 327.553, filed September 30. 1919, it is possible to control the efficiency of reception and transmission. This clearly shown in Figs. 1 and 1", the former representing the characteristic for receiving and the latter for sending. It'will be seen that in accordance with Fig. 1, the-system receives most efficiently waves advancing from the right and transmits most etliciently towards the left.

Since the arrangement shown in Fig. 1 is adjusted for reception from only one direction and for transmission in the opposite direction, it is obvious that it is useful only for one-way transmission of. signals. For practical operation itwould, of 'bourse, be necessary to have two of these. in one of which the receiving and sending characteristics. would be opposite to those of the other. Such a system is shown in Fig. 6, in which the upper dotted line between the two terminals represents the direction of transmission from terininal 1 to terminal 2, and the lower dotted line represents the direction of transmission between terminal 2 and terminal 1. In this arrangement the east repeater #1 would be operated so as to receive most efficiently along the line connecting the repeater with the terminal 1 and transmitting most efficiently along. the line extending from the east repeater #1 to the east repeater #2. If the transmission between the two terminals is effected by the same frequency, singing between the re peaters may be greatly minimized by wide geographical separation of the repeaters, as shown in Fig. 6.

The arrangement shown in 2 is differentiated from that shown in Fig. 1, however, by the use of separate arrays of antenme for receiving and sending. Thus, the antennae X,, X, and X belong to the receiving array and antennae X,, X, and X. belong" to the transmitting array. It may be stated that although the axes of the two arrays, as shown in the figure, are along different lines, the arrays may be arimnged so that their axes will coincide. The characteristic of the receiving array is that shown in Fig. 1, and the characteristic of the transmitting array is as shown in. Fig. 1". tennae X,, X, and X, are transmitted through the phase shifting devices, and the band filters, and the low power amplifiers of the local circuit and are impressed upon the common transmission line L,, that connccts the circuits of the receiving antenna with the circuits of the transmitting untenna. The currents transmitted over the line L, are amplified by the power amplifiers and after passing through the band filters are given the proper phase adjustment before being appliedl to the transmitting antcnnzc X,, X and X In-the arrangement shown in Fig. :2, singing is prevented. by the directive characteristics of the two arrays.

The arrangement shown in Fig. 8 is adapted for the simultaneous transmission and reception of two signaling channels. The antenna X, is designed for the reception of two channels, one represented by f,:':s, and the other represented by his. A band of frequencies represented by fi s received from the direction represented by the major axis of the loop characteristic 3 will be impressed upon the local amplifying circuit connected with the antenna X, by means of the transformer T,. The current resulting therefrom will be innpressed by the transformer '1 upon the circuit 1, which has connected therewith a phase shifting device PS, and a band filter F,, which latter device is adapted to transmit a band of frequencies represented by f s. The-current of the frequencies within the said band will be amplified first by the low power amplifier A, and then by the power amplifier The amplified current of this frequency range will pass through the band filter F and through the phase shifting device PS, and will be impressed upon the antenna by the transformer T for transmission at the frequency of f is. Simultaneously with the amplification of the signals represented by the band fl s. other signals within the range f s may be received, amplified and transmitted from this repeater device. Let it be assumed that signals based upon the carrier frequency f, are received along the line of major axis of the characteristic 3,

Oscillations set up .in the ans:

which direction is'opposite to that in which thesignals were received as represented by Fig. 3. The current resulting therefrom will be impressed upon the input circuit 2; which has associated therewith a phase shifter PS and a band filter F adapted re spectively to control the phase of the p re: ceived currents and to limit the range of frequencies to a band represented by ::8. Currents passing through the filter F, will be amplified, first by the low power amplifier A and then by the high power amplifier A and the resultant amplified current i will pass through the band filter F; By

means of the phase shifting devices such as PS associated, with the antenna X and, similar devices of the other antennae of the array, the wave will be radiated therefrom along the line represented by the characteristic of Fig. 3. It will be seen that int-he arrangement shown in Fig. 3 reception and transmission is eifectcd at the same frequency in each direction, tliat'is to say,the wave arriving from the east at the frequencyf will be radiated to the west at the same frequency and the wave arriving from the west at thefrequen cy f will be radiated to the east at the frequency f Singing through each unit circuit is prevented by means of the balancing network N and sim ilar net-works of the other unit circuits.

The arrangement shown in Fig. 4 differs from that shown in Fig. 3 principally in the use of a ground antenna for receiving in connection with a vertical antenna for transmission. Inthis way, singing of the amplifying circuit is prevented by the bal anced relation ofthe two antennae instead of by using a balancing network'such as shown in Fig. 3. Furthermore, both antennae of Fig. 4 have two degrees of freedom, thereby rendering the circuit adapted for duplex operation. Thereception frequency and transmission frequency for each individual channel is the same. This is clearly shown in Fig. 4, which represents four unilateral characteristics and not two bilateral ones. Thus, as shown in the latter figure signals of the frequency f, received from the west by the array of X, are amplified and transmitted towards the east at the same frequency by the array of X and in similar manner si als of frequency f,, received from the east y the array of X, are transmitted at the same frequency towards the west by the array of X .The arrangement shown in Fig. 4 may be adapted by the proper spacing of the antennae and by the proper adjustment of the amplitude and phase of the received and transmitted current to have. what is termed, the duolateral characteristic for receiving and transmitting, as shown in Fig. 5. Thus,

from that direction coinciding with the axis of the upper characteristic andmay be efliciently transmitted in the direction of the axis of thelower characteristic; and, simisi nals based upon the carrier fre quency inlay be efliciently received, from that direction coinciding with the axis of the lowercharacteristic and eilic-iently trans mitted in the direction of the axis of the upper characteristic; or signals may he efficiently received simultaneouslyfrom two directionscoinciding with the two axis'of the characteristics, and simultaneously transmitted in the same two directions away from the central point. l i V i It will therefore be apparent to those familiar with the art that by means of the arrangements set forth in the foregoing described figures, not only canradio signals be relayed or amplified but also that the direction of reception and transmission may lie-controlled so as to provide minimum interference with other signals in transmission and also to produce the greatest efficiency of operation. i

By means of the invention, which has been described in some of its various forms, the course of transmission of signals may be readily controlled, so that, if it is desirah le to use an indirect route between two termithe proper location of repeating stations embodying the principles of our invention.

Although this invention. has been described as embodied in a certain form and arrangement of parts, it is to be understood that it is capable of embodiment in other and different formswithin the spirit and scope of the appended claims.

lVhat claimed is:

1. In a radio repeating system the combination with a receiving antenna array of a transmitting antenna array, each co1nprising a plurality of antennae, and a plurality of connecting circuits each extending from an antenna of one array to an antenna of the other array, the said circuits containing means to amplify and means to change the phase of the currents in the said circuits. to effect unilateraldirectivity of the reception and transmission of radio signals.

52. In a radio repeating system the combination with a receiving antenna array of a transmitting antenna array, each of said arrays cmuprising a. plurality of antennae,

and both of said arrays designed to respond other array said circuitscontaining, means toamplify and means to change the phase of the currents in the said circuits to effect unilateral directivi-ty of the reception and transnr on of radio signals.

3. In a radio receiving system adapted to receive and transmit: signals at the same frequency the combination with a receiving array of a transmitting array and a plurality of circuits individual to each pair of receiving' and transmitting antennae having means associated therewith to amplify the received currents and means to control the phase of the currents transmitted in order to effect unilateral directivity of transmission.

4. In a. radio repeating system adapted to receiv and transmit signals at the same trequency the combination with a receiving array of a transmitting array anda plurality of circuits individual to each pair of receiving and transmitting antennae having means associated therewith to amplify the received currents and means to control the phase of the received currents in order to effect unilateral reception and means to control the pl-iase of the transn'iitted currents in order toeffect unilateral transmission.

5. In a radio repeating systen'l adapted for the simultaneous reception and transmission of a plurality of signaling channels the combination of a receiving antenna array responsive to two frequencies, a transmitting antenna array also responsive to two frequencies and a plurality of circuits connecting each pair of receiving and transmitting antennae adapted to control the phase of the received currents of each channel to effect unilateral reception and to amplify the said currents.v w

6. In a radio repeating system: adapted for the simultaneous reception and transmission of a plurality of signaling channels, the comthe simultaneous reception and-transmission ot a plurality of signaling, channels the com hinationi of a receiving antennaarray responsive to two trequcnciega transmitting antenna array also responsive to two frequencies and a plurality, of circuits-connecting cach pair of receiving and transmitting antennae having, means associated therewith to control the phase of the received currents and also having means' to centrol: the phase of the transmitted currents in order to eitect unilateral reception and transmission, and means to amplify the currents traversing the said circuits. 7 V V In testimony whereof, we have signed our names to this specification this 27th day of- December,1921l i LLOYD ESPENSCHIED. DE LOSS'K. MA .RTIN. 

